“Climate change remains one of the most pressing issues facing humanity today. If governments worldwide commit to reducing greenhouse gas emissions, there is a chance that global temperature increases can be limited to safer levels. However, if current trends continue unchecked, the consequences will be catastrophic, affecting ecosystems and societies alike. Scientists emphasize that, if early mitigation measures had been implemented decades ago, the severity of current impacts could have been significantly reduced.”
The sentence which correctly uses a conditional structure and maintains the intended meaning based on the context above is:
if the current trends will continue unchecked, the consequences will be catastrophic
if governments worldwide committed to reducing greenhouse gas emissions, global temperature increases could be limited
if early mitigation measures were implemented decades ago, the severity of current impacts will be significantly reduced
if scientists emphasize early action, the consequences were less severe